Described herein is a fuel authorization program that vehicles enrolled in the fuel authorization program to provide fuel tank sensor data in each fuel authorization request, so that an amount of fuel authorized will be limited to the amount needed to fill the vehicle's fuel tank, reducing a likelihood that fuel will be diverted. In at least some embodiments, the fuel authorization controller at the vehicle automatically uses the fuel tank sensor data and known tank size to include in a fuel authorization request sent to a fuel vendor data defining how much fuel is required to fill the vehicle fuel tanks. In at least some embodiments, the fuel vendor consults data from a source other than the vehicle (such as records maintained by the fuel authorization program) to determine how large the vehicles fuel tanks are, and to calculate how much fuel is required.